The present invention relates to the removal of hydrogen sulfide (H2S) from various gases, and more particularly it relates to the removal of hydrogen sulfide from a gaseous mixture using a filtering media containing iron hydroxide intimately bonded to calcined diatomite.
Hydrogen sulfide can be present in various air streams and is often found in gas streams associated with petroleum storage and transfer facilities, anaerobic digesters, sewage treatment plants and pulp and paper mills. In many cases, the hydrogen sulfide has to be removed because of its toxicity, corrosive properties, and unpleasant odour.
Several methods are known and have been used in the past for removing hydrogen sulfide from a gas stream. Perhaps the most popular method is one which consists in passing the gaseous mixture through an iron sponge bed. The iron sponge bed is a type of filter which comprises essentially iron salts adsorbed on a wood chip support media. Also, there are known processes in which a sulfurous gas is passed through a bed of iron oxide particles. These processes and various others are described in US Patents which can be found in particular in the US Classification 423/231 entitled: Removing Hydrogen Sulfide from a Gaseous Mixture Utilizing Iron Oxide or Hydroxide.
Problems associated with the prior art processes are numerous and include the facts that some media are self igniting when exposed to air and therefore are not renewable. Because of their weak sulfur retention, some of these non-renewable media must be treated as hazardous waste. Other known filtering media have a relatively low H2S adsorption capacity or a low H2S adsorption performance in a single pass process. Another drawback of some commercial H2S filtering systems is that the filtering media must be disposed of after a single use.
As such, it will be appreciated that there continues to be a need for a filtering process in which the filtering media is capable of removing hydrogen sulfide from a gaseous mixture with a high single pass performance. Further, it is believed that there continues to be a need for a filtering process wherein the filtering media is easily renewable and does not generate any hazardous waste when disposed of after multiple reuses.